Phonograph record



Patented Dec. 1948 l 2,457,154 rnoNoGmirn accom) James Il. Hunter,Bridgeport, Conn., assignor to I Columbia Records Inc., a corporation ofDela- Ware Application July 26, 1941, Serial No. 404,204

Claims. (CL 154-43) This invention relates to `a. phonograph record ofthe laminated type and it has for its objects the provision of a recordrelatively economical to manufacture having a playing surface of lowsurface noise" characteristic and of good wearing quality under constantuse.

The above objects are attained, according to the present invention, byproviding a relatively thick core adapted to substantially determine theover-all mechanical properties of the record after pressing, and a thinplaying surface of l an aggregate including a binder and a firstcomminuted filler material having irregular particles varying in sizefrom substantially less than a micron u p to the order of four micronsin largest dimension, and a second finely-divided filler material havingsubstantially uniform size particles of an order permitting readydispersion thereof both upon the surfaces of and between the irregularsize particles. The ratio of binder to the total amount of said fillersis such that, after pressing, the particles of the fillers arehomogeneously distributed in close relationl substantially withoutintervals therebetween.

As the result of extensive investigation, it has.

been found, contrary to the description lof United States Patent No.2,221,270, that the use of fillers having substantially uniform sizeparticles of the order therein described, yield what Will be termed abrittle playing surface having a high surface noise characteristic. Bythe use of an aggregate including a binder as above described,comparable to concrete aggregate, i. e., different size stones, sand,and cement, a playing surface having a very low surface noise isobtained which stands up under constant wear better than the playingsurfaces heretofore proposed. In addition, 'it has been found thataplaying surface in the form of an aggregate including a binder inaccordance with the invention, wears the point of the reproducing needleless than any shellac type record now upon the market. This may beattributed When manufacturing the improved records in accordance withthe present invention in the form of single or double face disc records,paper sheets coated with the playing surface material may be used' onone or both sides of the core material, as

Athe case may be. In the` record pressing operation carried out with thecustomary press, the relatively thick core serves as a mechanicalsupport for the thin playing surface or surfaces.

Core material suitable for use in accordance with the invention iscomposed esentially, for example, of green slate filler, cotton flock,and a binder such as shellac or resin or both. Since the core materialisemployed solely for the purpose of producing a relatively thick coreto provide support for the thin playing surface or surfaces, and toestablish the over-all mechanical properties of the record, itsconstituents may be varied, as will be readily understood. Anyone of thewell-known compositions for core material may be employed for thepurposes of the invention.

The following example illustrates a. preferred formula for the aggregateincluding the binder, to be used for the thin playing surface, partsbeing given by weight:

It will be observed that the shellac binder con- Calcium stearatestitutes approximately 25% by Weight of the agto the fact that theparticles of the flllers used In reducing the efl'ec- I gregate. Thus,the ratio of binder to filler is substantially one to three.

After thorough mixing of the above constituents, the powdered materialis appropriately applied to discs'of paper of suitable size for formingthe playing surface of the records.

The diatomaceous earth is comminuted by fine grinding to produceirregular particles varying in size from substantially less than amicron up to three or four microns in largest dimension. As is wellknown, this material is porous in structure.

The constituent 'Iibar HH is a precipitated pigment` of titanium dioxideand barium sulfate. The nature of the chemical precipitation is suchthat the particles are of substantially uniform,

size and of the order of one-quarter micron.

Due to the small particle size of the Tibar HH,

.it is readily dispersed into the pores and upon the surfaces of thediatomaceous earth particles.

The amount of shellac or binder employed and the ratio thereof to filler(diatomaceous earth and Tibar HH) is such that, after pressing, the

essaies particles of said fillers are hcmesenecusly distributed in closerel-ation substantially withoutv intervals therebetween.

Qther materials may be substituted for the material Tibar an; iorexample titanium dioxide A' per se or any other of the knownprecipitated and extremely fine fillers and the like. Also mixtures ofshellac and other natural and synthetic resins may be employed, such asthe natural resins conso gum and manila gum and the synthetic resins,for example, poly-vinyl acetate and its various derivatives.

A cross-sectional view of a laminated sound record made in. accordancewith the present invention is shown in the accompanying drawing.

Itis to be understood that the foregoing description of a preferredembodiment is set forth by way of example or illustration and that thethin playing surface of an aggregate inclu e.

'binder may be composed ofl various ingredients and produced in variousways for the particular purpose for which it is required and that theinvention is :not limited to these specific embodiv ments, except asdonned in the accompanying claims.

I claim:

tively thick core adapted to substantially provide the over-allmechanical properties of the pressed record, and a thin playing surfaceof an aggregate includingI a binder and a first filler of comminuteddiatomaceous earth having irregular d particles varying in size fromsubstantially less than a micron up4 to the order of four microns inlargest dimension, and a second chemically pre- .cipitated filler oftitanium dioxide and barium sulfate having substantially uniform sizeparticles of 'the order of one-quarter micron permitting readydispersion thereof both upon the 'surfaces of landlbetween saiddiatomaceous earth particles, the particles of said llers being, afterpressini.

homcgeneously distributed in close relation subst-antially withoutintervals therebetween.

1. A laminated sound record comprising a relaparticles varying in sizefrom substantially less I than a micron up to the order of four micronsin largest dimension, and a second iiller having substantially uniformsize particles of the order o! one-quarter micron permitting readydispersion 'thereof both upon the surfaces of and between saiddiatomaceous earth particles, the ratio of binder to ller being of theorder of one to three so that after pressing the particles of saidfillers i are homogeneously distributed in close relation substantiallywithout intervals therebetween.

2.v A laminated sound record comprising a relatively thick core adaptedto substantially provide the over-all mechanical properties of thepressed record, and a thin playing surface of an aggregate including a.binder and a first ller ci comminuted diaitomaceous earth havingirregular particles varying in size from substantially less than amicron up to the order of four microns in largest dimension, and asecond chemically precipitated filler of titanium dioxide and bariumsulfate Ahaving substantially uniform size particles of the order ofone-quarter micron permitting ready dispersion thereof both upon thesurfaces of and between said diatomacecus earth particles, the particlesof said fillers being, after pressing, homoseneously distributed inclose relation sub--V stantlally without intervals therebetween.

3. A laminated sound record comprising a relal tively thick core adaptedto substantially provide the over-all mechanical properties of thepressed record, and a thin playing surface of an aggregate including ashellac binder and a nrst filler of comminuted diatomaceous earth havingirregular i. A laminated sound record comprising a rela'- tively thickcore adapted to substantially provide the over-all mechanical propertiesof the pressed record, and a thin playingsurface of an aggregateincluding a binder and a nrst ller of comminuted diatomaceous earthhaving lirregular particles varying in 'size from'substantially lessthan a micron up to the order of four microns in' largest dimension, anda second ller comprising titanium dioxide and having substantiallyuniform size particles of the order of one-quarter micronv permittingready dispersion thereof both upon the surfaces of and between saiddiatomaceous'earth particles, the ratio of binder to `filler being ofthev order of one -to three so that after pressing the particles of saidiillers are homogeneously distributed in close relation substantiallyvwithout intervals therebetween.

5. A laminated sound record comprising a relatively thick core adaptedto substantially provide the overall mechanical properties of thepressed record, and a thin playing surface of an aggregate including abinder and a iirst 1111er of comminuted diatomaceous earth havingirregular particles varying in size from substantially less than amicron up to the order oi four micronsv in largest dimension, and asecond filler o! chemically precipitated flne material having substa.n.A

tially uniform size particles of the order of onequartermicron'permitting ready dispersion thereof both upon the surfaces,y ofand betweens-aid diatcxnaceous earth particles, the ratio of binder tofiller being of the order of one to three so that after pressing theparticles of said llers are.

homogeneously distributed in close relation substantially withoutintervals therebetween.

.TALES H. HUNTER.

REFERENCES CITED The following references are ci' record in the viiie oithis patenti UNITED STATES PATENTS Number Severin Nov. l2,

